Astronomy Picture of the Day

Explanation: The centre of well-studied active galaxy Centaurus A is hidden from the view of optical telescopes by a cosmic jumble of stars, gas, and dust. But both radio and x-ray telescopes can trace the remarkable jet of high-energy particles streaming from the galaxy's core. With Cen A's central region at the lower right, this composite false-colour image shows the radio emission in red and x-rays in blue over the inner 4,000 light-years of the jet. One of the most detailed images of its kind, the picture shows how the x-ray and radio emitting sites are related along the jet, providing a road map to understanding the energetic stream. Extracting its energy from a supermassive black hole at the galaxy's centre, the jet is confined to a relatively narrow angle and seems to produce most of its x-rays (bluer colours) at the upper left, farther from the core, where the jet begins to collide with Centaurus A's denser gas.